Compact heating and cooling system

ABSTRACT

A compact absorption refrigeration unit has a central mounting core containing a generator about which substantially all of the components of the refrigeration system are mounted in a predetermined configuration. The generator has heat transfer fins secured to its surface which have a predetermined configuration that allows the fins and generator to absorb heat at the optimum rate at which heat can be transferred thereto without damage to the fins. The unit also includes an evaporator having a centrally positioned reservoir and a helical passageway providing a flow path for a heat exchange medium and containing a fluted helical heat exchanger tube which provides a countercurrent refrigerant, thereby to chill said heat exchange medium. In one embodiment of the invention the unit is provided with a compact boiler for use in heating the heat exchange medium, thereby permitting the unit to be selectively operated for both heating and cooling.

United States Patent [191 Mallosky et al. I

[11] 3,828,575 1 Aug. 13, 1974 COMPACT HEATING AND COOLING SYSTEM [75]Inventors: Norman D. Malcosky; Ronald H.

McLean, both of Columbus; Kanwal N. Singh, Westerville; Chung M. Auh,Columbus, all of Ohio [73] Assignee: Columbia Gas System ServiceCorporation, Wilmington, Del.

[22] Filed: Apr. 13, 1973 [21] Appl No.: 350,822

Harold L. Stults, Curtis, Morris & Safford [57] ABSTRACT A compactabsorption refrigeration unit has a central mounting core containing agenerator about which substantially all of the components of therefrigeration system are mounted in a predetermined configuration. Thegenerator has heat transfer fins secured to its surface which have apredetermined configuration that allows the tins and generator to absorbheat at the optimum rate at which heat can be transferred theretowithout damage to the fins. The unit also includes an evaporator havinga centrally positioned reservoir and a helical passageway providing aflow path for a heat exchange medium and containing a fluted helicalheat exchanger tube which provides a countercurrent refrigerant, therebyto chill said heat exchange medium. In one embodiment of the inventionthe unit is provided with a compact boiler for use in heating the heatexchange medium, thereby permitting the unit to be selectively operatedfor both heating and cooling.

17 Claims,- 7 Drawing Figures OOO OOOOOOO Pmmwwww 3.828.575 SHEET 1 (IF4 I PAIENTED M1 Y 3 974 SHEET 2 0F 4 OOOOOOOOOO\ Fig. 3

PAIENI AUG I 3mm sum u or 4 REFRIGERANT CONDENSING UNIT I09 AIR TREATINGUNIT IZO LIQUID HEATER COMPACT HEATING AND COOLING SYSTEM The presentinvention relates to air conditioning systems and, in particular, to acompact air conditioning system which may be selectively operated foreither cooling or heating the air conditioned space as desired.

There has recently been an increased demand for air conditioning heatingand cooling units for use in residential space conditioning. Inparticular, the demand has increased for gas fired air conditioningunits which are compact in size and quiet in operation while maintaininghigh standards of performance and reliability and with minimum serviceover extended periods of time.

In order to limit the amount of space occupied in a home or residentialbuilding by the air conditioning and heating systems, it has becomedesirable to produce residential gas air conditioning systems which canalso serve as a heating system during the winter months and thus providecomplete space conditioning for residences in a single unit or package.Another feature which is desired in air conditioning systems for homesis that the system be located out of doors, thereby to provide moreoccupiable space within the residence itself.

Accordingly, it is an object of the present invention to provide aneconomical, inexpensive and reliable air conditioning system forresidential use. I

Yet another object of the present invention is to provide spaceconditioning systems which satisfy the abovementioned demands anddesires.

A further object of the present invention is to provide efficient andeconomical components for such systems.

In accordance with an aspect of the present invention, a compact airconditioning system is provided which includes a central, generallycylindrical hollow core on which substantially all of the components ofthe air conditioning system are mounted or supported. The core and theair conditioning components are enclosed within a removable framestructure which is not connected to any of the air conditioningcomponents, so that the entire air'conditioning system and itscomponents can be conveniently exposed for assembly, inspection andrepair. In one illustrative embodiment of the present invention, thespace conditioning system is used to cool the interior of a building,e.g. a residential structure, and is located outside of the building,with only an air distribution plenum system, and a fan/coil heatexchanger unit located within the building, In another embodiment, thesystem can be readily converted to one whichwill selectively provideboth-cooling and heating.

In one preferred embodiment, the compact space conditioning system ofthe present invention includes a vapor generator assembly which isadapted to receive a strong refrigerant solution which is heated by agas fired combustion means located below the generator to producerefrigerant vapor. A heat exchange condenser is connected in fluidcommunication with the generator for receiving and condensing thegenerated refrigerant vapor, with the cooled refrigerant liquid flowingfrom the condenser through a refrigerant heatexchanger. The latter isconnected in fluid communication with a heat exchange evaporator,through a first restriction means, whereby cooled refrigerant liquid issupplied to the evaporator for cooling a heat exchange medium flowingtherein. The refrigerant heat exchanger receives refrigerant vapor fromthe evaporator and passes it countercurrently with the refrigerantliquid flowing from the condenser to the evaporator, thereby to furthercool the refrigerant liquid prior to passage through the firstrestriction means to the evaporator. In addition, a heat exchangeabsorber is connected in fluid communication with the refrigerant heatexchanger and with a solution heat exchanger. Weak refrigerant solutionis supplied from the generator through the solution heat exchanger tothe absorber wherein the weak solution absorbs refrigerant vaporsupplied from the evaporator. A second fluid flow restriction means islocated between the solution heat exchanger and the absorber formaintaining a pressure differential therebetween. A solution pump isprovided for pumping strong refrigerant solution produced in theabsorber and supplying a first portion thereof directly to a rectifierheat exchanger, and a second portion thereof to the top of the analyzervia a solution heat exchanger, wherein the strong refrigerant solutionflows in heat exchanger relation to the weak solution. Thus, heat isadded to the second portion of the refrigerant solution prior to passageinto the generator. In another embodiment of the invention, the airconditioning system is provided with a selectively operable boiler bywhich the system is conveniently converted from a cooling mode ofoperation to a heating mode.

The present invention provides an air conditioning system which isrelatively compact in construction, since all of the components thereofare mounted on a single central core, in a close compact relationship toone another, so that the system can be conveniently installed out ofdoors adjacent the building to be conditioned and in as inconspicuous alocation as possible. Accordingly, the air conditioning system does notoccupy any valuable floor space within the building.

The above, and other objects, features and advantages of this invention,will be apparent in the following detailed description of anillustrative embodiment thereof which is to be read in connection withthe accompanying drawings wherein:

FIG. 1 is a perspective view of a space conditioning unit constitutingone embodiment of the present invention;

FIG. 2 is a diagrammatic view of the components'of the spaceconditioning unit illustrated in FIG. 1',

FIG. 3 is a sectional view, with parts broken away, taken along line 3-3of FIG. 1; I

FIG. 4 is an enlarged vertical section of the vapor generator assemblyutilized in the space conditioning unit of the present invention;

FIG. 5 is a plan view of a heat transfer fln utilized in the vaporgenerator assembly of FIG. 4;

FIG. 6 is an enlarged sectional view of the evaporator of the unit ofFIG. 1; and

FIG. 7 is an exploded perspective view of the compact boiler of the unitof FIG. 1.

Referring to FIGS. 1 and 2 of the drawings, it is seen that the spaceconditioning unit 10 of the present invention, which includes a gasfired absorption refrigeration system and a gas heating unit, isgenerally cylindrical with an outer casing or shell structure 12. Casing12 includes a lower wall 14 formed of panels of corrugated sheet metalsecured to each other by a plurality of screws 16. These panels aremounted upon a base 18 formed by a circular bottom wall 17 and aperipheral flange 19 (FIG. 3) for supporting the various components ofthe entire air conditioning unit.

The main structural component of the air conditioning unit is a centralcore 20 (FIG. 3) which is centrally mounted on base 18 and provides anenclosure for the generator assembly and asociated components of theunit. Core 20 is formed by lower and upper cylinders 54 and 56 and afrustroconical collar 52 mounting cyliner 56 in vertical axial alignmenton cylinder 54. This core provides support for substantially all of theother components of the unit.

Each of a plurality of radially extending arms 22 is secured to core 20and provides support for an intermediate annular support plate 24.Corrugated panels 14 are secured between base 18 and arms 22 and providea lower enclosure for various components of the unit. The upper portionof the unit is enclosed by a cylindrical, foraminous casing wall 28which is formed of perforated sheet metal that defines a large number ofrelatively uniform openings 29 providing communication between theatmosphere and the interior of the unit, thereby permitting ambient airto flow into and through the upper portion of the unit. Casing wall 28is supported on and secured to, support plate 24 in any convenientmanner. The top of the unit is closed by a lid 34 resting upon aperipheral ring 35 secured to wall 28. Lid 34 has an open wire top 36,which permits ambient air to flow from the top of the unit.

As indicated above, unit includes an absorption type refrigerationsystem which hasa vapor generator assembly 38 enclosed within centralcore 20. Generator assembly 38 is enclosed within a generallycylindrical pressure vessel to which a strong aqua-ammonia solution issupplied and in which refrigerant vapor is driven from the solution uponheating by a gas burner assembly 40. Burner assembly 40 produces a flamefront below the generator assembly 38 within the annular flue passages48 of the generator assembly. The burner assembly is of the semi-poweredblue flame type since combustion air is supplied to the venturi of theburner as a result of the slight vacuum created in the unit by thecondenser fan 100, more fully described hereinafter. This fan draws airin the unit and thus supplies air to the burner, which air is 100percent premixed with the fuel gas so that no secondary air is requiredto complete the combustion process. This burner has an extremely shortflame height; that re duces the'overall height of the unit. Moreover,the airto-fuel ratio is substantially stochiometric so that a peak flametemperature and a maximum efficiency are obtained. g

The combustion products of burner assembly 40 are confined to an annularflue 48 adjacent the outer heat transfer surface 44 of generatorassembly 38 up to the level of plate 24 by an insulation liner 46 on theinner surface of cylinder 54 of central core 20. The products ofcombustionare discharged from flue 48 through apertures 50 in collar 52.

The heat transfer from the products of combustion to the generator isprovided by uniquely shaped heat transfer fins 58 (see FIGS. 4 and 5)welded to the lower portion of the heat transfer surface 44. The widthof the fins 58 vary along their length l, which length in the preferredembodiment of the present invention is 13 /2 inches, so that each finabsorbs heat without damage at the same rate at which heat will passthrough the fin and the heat exchange wall to the fluid containedtherein when the temperature at the edge of the fin is near, but lessthan the maximum permissible temperature for the tin. By thisarrangement, the fins do not have excessively hot spots along theirsurfaces and the life of the structure is prolonged.

The configuration of the outer edge of each of fins 58 will, in theoptimum configuration, conform to a developed curve of predeterminedcharacteristics. However, in the preferred embodiment of the invention,the edge configuration of the fins is formed by straight edge sectionsof predetermined slopes and the overall effect is an acceptabledeviation from the optimum curve. Thus, as shown in FIG. 4, fins 58 areconstructed so that the lower portion thereof has a length 1 (preferably2.4 inches long) along which the fin extends from a minimum width (of0.5 inches) to a first intermediate width (of 1.50 inches). Along thislength of the heat exchanger fins, the combustion product gases are atrelatively high temperatures and thus the dimensions of the fins must besmall in order to prevent their becoming overheated by contact withthose products of combustion. Along the length 1 (preferably 4.5 incheslong),

fins 58 further expand their width to a maximum width (of 2 inches) atan intermediate point along their length. Along this portion of thelengths of the fin, the products of combustion are channeled between thefins toward surface 44 into the greater fin width, to transfer heat tothe generator, without excessive heating of the fins. This is animportant feature of the invention since the hotter gases adjacent liner46 are gradually channeled or directed towards the inner portions of thefins to improve heat transfer without overheating the fins or creatinghot spots such as would cause oxidation of the fins. Overheating and/orhot spots in the fins also is undesirable since it will cause breakdownof the refrigerant in the generator.

Finally, along a length 1 (preferably 5.5 inches), the width of the finsis of a uniform dimension of 2 inches, and the edges 60 of the fins abutthe surfaces 62 of the insulated liner 46 on the interior of cylinder54. Accordingly, it is seen that the distance between the edge 60 andtheinside surface 62 of insulation 46 steadily decreases to an intermediatepoint along the lengths of the fins so that the flue gases progressivelyencounter the edges of the fin and are forced into the passagewaysformed between the fins. In this manner, as the combustion productsbetween the fins cool and heat transfer drops, the higher temperaturecombustion products adjacent the outer ends of the fins are forced intoand between the passages of the fins so as to maintain rela tivelyuniform heat transfer with the generator, to improve and obtain a moreefficient heat transfer between the combustion products and generator38.

In addition, since fins 58 extend parallel to each other, all of theheat exchanger surfaces are constantly swept by the combustion products,thereby improving heat transfer. Moreover, the construction of thegenerator, with the annular flue 48 in which fins 58 are located createsa slight pressure differential in the flue under the influence ofcondenser fan 100. The pressure differential created by condenser fan inthis manner acts through the burner to draw ambient air through theventuri of the burner 40, thereby providing 100 percent aeration for theburner to obtain maximum efficiency therewith.

In the preferred embodiment, fins 58 (see FIG. 5) are in pairs, witheach pair having a generally channelshaped configuration with a bightportion 64 welded to the heat exchange wall 44 of generator 38. Thebight portion 64 has a series of spaced slots 66 along its length andthe welding metal fills the slots. As a result, heat is transferredefficiently from the combustion products through fins 58 to the walls 44and thence to the fluid in the generator. Alternatively, fins 58 may beformed as separate independent plates welded or otherwise secured to thegenerator.

As mentioned above, a stream of strong aquaammonia solution is suppliedto the generator assembly in order to produce refrigerant vapor and weakrefrigerant solution. The refrigerant vapor produced in the generatormoves upwardly towards the top of the generator assembly for use in theair conditioning system,

as described hereinafter, while a weak solution at an acceptable levelremains in the generator. This level generally extends to a positionadjacent the top of an analyzer assembly 70 contained within thegenerator; and preferably to the level of a refrigerant check tube 69extending from the generator wall 38.

The weak solution flows from the generator, due to the pressure therein(as described more fully hereinafter) through a heat exchanger tube 68of the analyzer assembly 70 contained within the generator. Tube 68 is ahelix of a diameter so that it is spaced from the inner surface ofvessel 38 and extends axially from the bottom of the generatorassembly'upwardly above the level of plate 24. (It is noted that in FIG.4 of the drawing, the central portion of the tube 68 has been brokenaway for clarity.)

Coaxial with tube 68 is the analyzer assembly 70, formed by a centralmounting post 71 supported on the bottom wall 42 of vessel 38. Thismounting post has a hollow lower end portion which receives the curvedlower end 73 of tube 68. By this construction the opened end 73 isdirected away from the bottom of the generator and does not pick up,with the weak solution, any sediment lying on the generator bottom.

A series of mass transfer baffle plates 72 are mounted on post 71, witheach of the plates being slightly more than one-half of a disk havingthe radius of the inner surface of vessel 38. The plates are mountedupon post 71 in alternated right and left relationship, as shown. Hence,one plate forms a baffie from one side of the vessel to beyond the posttoward the opposite side, and each of the adjacent baffles form similarbaffles from that opposite side .beyond the post toward that one side.This construction forms a liquid-vapor counterflow relationship betweenthe liquid flowing downwardly back-and-forth from plate to plate, andwith vapor flowing upwardly.

Cool strong solution is supplied to the generator (as describedhereinafter) and flows downwardly under the influence of gravity. Thiscooled solution passes over plates 72, and over the windings of the heatexchanger tube 68, so that it exchanges heat with the hot weak solutionflowing in tube 68. As a result, additional heat is supplied to thestrong solution, thereby to produce vaporization of the refrigerantvapor therein, and the weak solution leaves the analyzer highlysubcooled through an outlet 74 in tube 68.

From outlet 74 the weak solution passes through an external solutionheat exchanger 76 where. further cooling of the weak solution takesplace. The solution heat exchanger comprises a helically woundtubewithin-a-tube assembly located concentrically around the upperportion 78 of vessel 38, between the exterior wall of the vessel and theupper portion 56 of center core 20 (see FIG. 3).

Solution heat exchanger 76 is used to transfer heat between the weaksolution from the generator and a portion of the strong solutionreturning to the generator from the absorber. The weak solution flowsthrough the inner tube 80 of the heat exchanger. This tube extends intoand through a large diameter outer tube 82, through which the strongsolution flows with the weak solution and strong solution flowingcountercurrcntly to each other in their respective tubes.

Solution heat exchanger 76 increases the thermal efficiency of theoperating cycle of the air conditioning system, since heat must besupplied in the generator to the returning strong solution in order tovaporize the refrigerant and heat must be rejected from the weaksolution in the absorber portion of the operating cycle. Thus, theexchange of heat between the streams of weak solution and returningstrong solution reduces both the required heat input to the strongsolution in the generator and the heat rejection from the weak solutionin the absorber. As a result, a lower gas input rate is required in theburner 40 for boiling the ammonia vapor out of the refrigerant solutionin the generator.

The weak solution, which is now highly subcooled by passage throughsolution heat exchanger 76, passes from the heat exchanger through arestrictor 84, i.e. a capillary tube, to the low pressure side of thesystem. After passing restrictor84 the weak solution enters an absorber99 wherein the weak solution absorbs refrigerant vapor prior to returnto the generator.

The refrigerant vapor from generator 38, which rises toward the top ofthe generator contains water vapor which must be removed from therefrigerant vapor. A portion of this water vapor is removed in theanalyzer section of the generator wherein analyzer plates 72 function toprovide maximum mass transfer contact between the countercurrent liquidand vapor streams so that the aqua-ammonia vapor directly contacts thecooler strong solution returning to the generator to cause condensationof some of the water vapor in the stream and vaporization of some of theammonia in the strong solution droplets. Further purification takesplace in the rectifier portion 75 of generator 38. Rectifier 75 islocated in vessel 38 directly above the analyzer section and includes atubular heat exchanger 86 which is helically wound around a closedhollow cylindrical core 86'. A portion of the strong solution flowsdownwardly to the analyzer through tubular heat exchanger 86 and coolsrefrigerant gas vapor rising from the analyzer to cause furthercondensation of water vapor from the gas. The hollow cylindrical core 86within heat exchanger 86 serves to prevent the refrigerant gas vaporfrom flowing through the center of the heat exchanger and thus forcesthe vapor across the outer surfaces of the heat exchanger, to improvecondensation. The water condensate from the refrigerant vapor streamdrips downwardly on the outside of the rectifier heat exchanger 86 tothe lower portion of the generator assembly thereby to form a portion ofthe weak solution.

In addition, the rectifier portion of the generator assembly includes aRaschig ring bed 92 at the lower section of the rectifier heat'exchanger86 wherein the condensate formed in the rectifier on the surface of theheat exchanger 86 is refluxed prior to passage into the analyzer sectionof the generator.

The heat of condensation of the water vapor in the rectifier raises thetemperature of the strong solution supplied through heat exchanger 86,thereby further reducing the requirement for heat from burner 40. Thestrong solution flows from the end 88 of heat exchanger 86 through aplurality of apertures 90 onto the top plate of the analyzer section ofthe generator. This strong solution combines with the other portion ofthe strong solution flowing from the solution heat exchanger and passesthrough analyzer 70, exchanging heat and mass with the countercurrentvapor stream, and exchanging heat with the weak solution in the analyzerheat exchanger 68.

The substantially pure ammonia refrigerant vapor at the top 94 ofpressure vessel 38 leaves the vessel under pressure through conduit 96and enters the condenser 98 wherein the vapor is cooled and condensed.It is noted that both the condenser 98 and absorber 99 'are formed asfinned, helically wound heat exchanger coils. These coils are locatedabout the periphery of center core and are positioned in adjacent andsuperimposed relationship to one another, as seen in FIGS. 2 and 3. (Forconvenience, the fins of the condenser 98 have been shown in FIGS. 2 and3 with cross-hatched shading, whereas those of the absorber 99 have beenleft clear.) The heat transfer coils of the absorber and condenser aresupported on the central'platform 24 which, in turn, is seated on andsecured to the radially extending ribs 22 secured to core 20. In thismanner, the arrangement of the components of the conditioning system aremade as compact as possible.

In this configuration, both the absorber and the condenser are exposedto ambient air flowing through exterior grid 28. In order to draw thisambient air through grid 28, a fan 100 is mounted at the top of centralcore 20, and is driven through a belt and pulley arrangement 102, asschematically illustrated in FIG. 3 of the drawing, from a motor-pump104, as more fully described hereinafter. r

After an initial rapid drop in the temperature of the ammoniarefrigerant vapor in the condenser, most of the refrigerant vaporiscondensated in the condenser at essentially constant temperature(under the influence of air drawn thereover by fan 100); with the liquidrefrigerant leaving the condenser slightly subcooled. From the condenser98 the liquid refrigerant is passed through a conduit 106 to arefrigerant heat exchanger 108 inwhich the liquid refrigerant exchangesheat with cooler-counterflowing two phase refrigerant mixture leavingthe evaporator 1100f the air conditioning system.

Conduit 106 includes a cut restrictor 107 positioned therein between thecondenser 98 and the refrigerant 'heat exchanger 108. This restrictorserves to maintain the refrigerant in the condenser at an elevatedtemperature and pressure, thereby to obtain improved heat transfer inthe condenser with the ambient air and reducing the amount of surfacearea which would be required for the condenser. Typically, therestrictor proflows into heat exchanger 108.'In the latter therefrigerant vapor is recondensed and thus further improves the heatexchange taking place therein.

Refrigerant heat exchanger 108 also constitutes a helically woundtube-within-a-tube heat exchanger (of the type described with respect tothe solution heat exchanger) in which the liquid refrigerant from thecondenser passes through a first or outer tube 112 and is cooled by thecooler refrigerant returning from evaporator within an inner tube 114.By thus further cooling the liquid refrigerant passing to the evaporator110, the thermal efficiency of the entire air conditioning system isfurther increased. The refrigerant heat exchanger also is supported onthe intermediate support pan 24 (FIG. 3) so as to provide as compact aconfiguration as possible. I

The now highly subcooled liquid refrigerant is then passed through anoutlet conduit 116 to an expansion valveor capillary tube 118, whereinthe subcooled liquid is throttled at constant enthalpy from the highpressure side (condenser) of the system to the low pressure side(evaporator) of the sysaern; Typically, the throttling process throughthe restrictor causes a small fraction, usuallyless. than 10 percent ofthe liquid, to flash into a vapor within the restrictor itself, therebyfurther reducing the temperature of the refrigerant.

Evaporator 110 is the structure in which the heat exchange medium thatis to be chilled by space conditioner 10 is passed. Typically, the heatexchange medium is supplied to the heat exchanger unit of an air/- coilsystem in which ambient air is blown over a heat exchanger coil withinthe home, cooled (or heated) thereby, and supplied through a plenum orduct work system throughout the variousrooms of the house. In thepreferred embodiment of the invention the heat exchange medium used inthe evaporator 110 is an ethylene. glycol solution, which will notfreeze during the winter months.

As illustrated in FIG. 6 of the drawing, evaporator 110 comprises anouter cylindrical vessel 120 which has a vertical axis and contains aninner cylindrical sump tank 122. Tank 122 has an aperture 124 at itsbottom which provides communication with an annular space 126 formedbetween thetank and vessel 120. The latter is covered by an insulationlayer 128, and is mounted on base 18 adjacent core 20, below thecondenser and absorber. A spiral vane or baffle 130 is secured to theperiphery of tank 122 and has a width equal to the width of the annularspace 126 so that the baffle forms a closed spiral heat exchange conduitor passage 134.

Heat exchange medium returning from the air coil unit in the house issupplied through an inlet port 132 to the uppermost portion of thespiral conduit 134. As

a result, the heat exchange medium is forced to flow downwardly alongthe spiral path of conduit 134 to the base of evaporator 110 wherein itis discharged through a conduit 136 for supply to the air/coil unit.Conduit 136 is connected in any convenient manner to a suitable pump138, which causes the heat exchange medium to flow to and from theair/coil unit in the house.

Evaporator 1 10 has a top opening 139 through which capillary tube 118extends downwardly through the center of tank 122. The liquidrefrigerant from the refrigerant heat exchanger 112 passes throughcapillary tube 118, and the interior of core 122, to the inlet endcountercurrently through the evaporator, with the heat exchange medium,thereby to chill the heat exchange medium during the air conditioningmode ofoperation of the device. In order to provide improved airconditioning operation, fluted tube 144 has a generally squarecross-section, as seen most clearly in FIG. 6, and is twisted about itslongitudinal axis so as to form a spiral configuration throughout itsentire length. This spiral configuration improves the contact of theheat exchange medium with the surface of the tube 144 as the heatexchange medium flows through conduit 134, thereby to enhance the heattransfer between the cold two phase refrigerant mixture within the tubeand the heat exchange medium flowing over the exterior in conduit 134.

It is noted that capillary tube 118 passes through the aperture 124formed in the lower portion of core 122 for connection to the end 142 oftube 144. As mentioned, this aperture serves to provide liquidcommunication between the interior of the tank 122 and annular space 126(and thus conduit 134), whereby the center of tank 122 acts as areservoir for extra chilled heat exchange medium. Moreover, as describedhereinafter, during the heating mode of operation of the conditioningsystem of the present invention, this chamber (i.e. the interior of tank122) acts as an expansion chamber for the heat exchange medium.

An additional conduit 136 is connected to evaporator 110 and extendstherethrough into interior tank 122. The right end of this tube isconnected, outside of the evaporator, to a plastic tube or the like (notshown) by which the .liquid level in the tank 122 can be checked. Thatis, by holding the plastic tube vertically, the tank'122, conduit 137and the plastic tube act as a manometer. Of course, the plastic tube maybe provided with a pinch valve or the like to prevent discharge of fluidfrom tank 122.

From evaporator 110, the two phase refrigerant mixture passes throughconduit 140 to the inlet side of tube 114 in refrigerant heat exchanger108, wherein it serves to cool refrigerant flowing in tube 112 fromcondenser 98. From tube 114, thetwo phase refrigerant mixture flowsthrough a conduit 142 to absorber 99. As the two phase refrigerantmixture enters absorber 99, it is mixed with the weak solution flowingthrough capillary tube 84 from generator 38 and solution heat exchanger76. As a result, the weak solution absorbs refrigerant vapor in the twophase refrigerant mixture. The heat released by the absorption processtaking place in absorber 99 is discharged or rejected from the absorberby the ambient air which is drawn over the absorber by fan 100, and thusis rejected into the atmosphere.

From absorber 99, the now strong solution refrigerant liquid is passedthrough a purge pot or reservoir 145 to pump 104. The latter is mountedon the outer surface of the upper portion 56 of center core 20 and isconstructed in accordance with the hermetically sealed pump shown anddescribed in U.S. Patent application Ser. No. 313,756, filed Dec. ll,1972, the disclosure of which is incorporated herein by reference. Pump104 draws solution from absorber 99, increases its pressure anddischarges the strong liquid refrigerant solution along two lines 87 and148.

Conduit 87 supplies a first portion of the strong solution directly tothe rectifier heat exchanger in the upper portion of the generator,wherein the solution is heated by the condensation of water vapor on theouter portion of tube 86 and by the passage of refrigerant vaporupwardly to the top of the generator. Line 148, on the other hand,supplies a second portion of the strong solution to the outer tube ofsolution heat exchanger 76, wherein it passes in countercurrent heatexchange relation with weak solution flowing from generator 38, throughconduit 74, thereby to further increase the temperature of the strongsolution and decrease the temperature of the weak solution passing tothe absorber. The strong solution passes from the solution heatexchanger through conduit 150, wherein the solution issupplied through aplurality of apertures 152 in the free end 154 of conduit 150 directlyabove the uppermost analyzer plate 72 of analyzer 70.

Accordingly, the refrigeration cycle is completed. As thus described,the space conditioning system of the present invention is adapted to beused as a highly efficient air conditioning system for cooling theinterior of a home or the like. In one preferred embodiment of thepresent invention the system is constructed to produce 36,000 BTUs perhour of cooling capacity. The cooling system operating in this mode hasproved to be highly satisfactory, efficient, quiet and to have anextended useful life, over and above that of the previously proposedsystems. Moreover, because of the compact construction of the airconditioning system, with substantially all of the components mounted onor otherwise supported by the central core member 20 in a predeterminedplanned configuration, a compact assembly is provided in which each ofthe components is independent of the exterior framework of the system.Thus, the components are readily accessible for repair and the exteriorshell of the system can be conveniently remonths. In this embodiment ofthe invention the system is provided with a compact water boiler 160,located downstream of the heat exchange medium pump 138. This boiler islocated within the shell 10 of the space conditioning system and ismounted on center core 20, or otherwise secured to or supported in thelower pan 18 of the system.

In the heating mode of operation of the invention, burner 40 is not inoperation and the air conditioning components are inactive. Thus, theheat exchange medium flowing between the evaporator and the air/- coilunit in the residence, simply flows into evaporator 110 through inlet132, through spiral conduit 134, and is discharged through the conduit136 to pump 138. The latter supplies the heat exchange medium to boiler160, wherein the heat exchange medium is heated to the desiredtemperature and supplied through conduit 162 to the air/coil unit withinthe house.

On the other hand, in the air conditioning mode of operation, the heatexchange medium will also flow through boiler 160, as illustrated inFIG. 2 of the drawing. However, the boiler will be inoperative (i.e.shut off) but heat exchange medium will flow through the heat transfercoil within the boiler. By the novel and unique construction of boiler160 the temperature of the chilled heat exchange medium flowing throughthe boiler is not substantially effected as it passes therethrough.

Boiler 160 is more clearly illustrated in FIG. 7 of the drawing; as seentherein, the boiler includes a powered air blower 164 for pressurizingambient air and supplying the same with gas to the burner 166. Thecombustion blower 164 mixes the gas supplied from a gas supply line (notshown) with the required amount of air and forces the mixture through aframe holder screen 168. The flame holder preferably is formed of a meshlnconel wire screen located above a plenum chamber 170 in which there islocated an antiflashback wire screen, adjacent the outlet 172 of thecombustion blower. Preferably, flame holder 168' has a size of sixinches by three inches,- and is located directly below a series ofcopper finned heat transfer tubes 174.

Heat transfer tubes 174 arev arranged in a stacked configuration, withthe lowermost tubes 174a in fluid communication with a header 176 towhich the heat exchange medium is-suppliecl from pump 138. The heatexchange medium flows through the lowermost-tubes 174a, thence through amanifold (not shown), upwardly to the heat exchange tubes 174b andacross the flame holder 168 in an opposite direction; thence through Utubes 178 to the uppermost tubes 1740; and thence through an outletdischarger head 180 to the conduit 162.

In a preferred embodiment of the invention, the fins on the lowermostpair of tubes 174a have an external diameter which is less than thediameter of the fins on tubes l74b. The fins on the latter tubes, inturn, have a smaller diameter than the fins on the tubes 1740. This isdonebecause the products of combustion encounter tubes,l74a beforetubesl74b and in turn before tubes 174a. Sincethe temperature of the productsof combustion is higher when they encounter tubes 174a, the smaller finsare used to transfer less heat to the tubes and the heat exchange mediumcontained therein, thereby preventing damage to the fins on thelowermost tube, while-also preventing any thermal degradation byoverheating of the heat exchange medium flowing within the tubes.

Preferably boiler 160 is provided with slotted baffle plates 188, 189between the pairs of tubes 174, as illustrated in FIG. 7 of the drawing.These baffles serve to divert the products of combustion around theentire periphery of each of the heat transfer tubes to provide bettercontact therebetween and thus better efficiency in transfer of heat fromthe products of combustion to the heat exchange medium passing throughthe tubes.

The burner portion 166 of boiler 160 is covered by a shroud 182, ofsheet metal construction, having combustion products exhaust 184 whichcompletely encloses the burner portion of the boiler so as to insureefficient contact of the combustion products with heat exchanger tubes174. Preferably the boiler construction is mounted on a frame 185 whichis in turn secured by welding or the likethrough a bracket 186 to thecenter core 20 of the space conditioning system. It is also noted thatthe exterior walls 187 of the boiler are preferably insulated with ahigh temperature insulating material 190 to insure that substantiallyall of the heat of the products of combustion is transferred to the heatexchange medium and is not lost through the walls of the boiler.Finally, it is noted that because of the relatively small area of theflame holder and combustion blower outlet 172, through which the heatexchange tubes 174 are exposed to atmospheric conditions during the airconditioning cycle of operation of the present invention, there is aminimum cooling loss by natural convection throughthe boiler during theair conditioning cycle.

Pump 138, used to circulate heat exchange medium from the airconditioning system 10 of the air coil unit located within the house orresidence, can be provided in two different embodiments. In oneembodiment pump 138 may simply be a centrifugal pump driven by a belttakeoff arrangement (not shown) from the drive shaft of the motor 104.The driven centrifugal pump is used when the system is built to functiononly as an air conditioner, since in that mode of operation the-heatexchange medium is pumped to the house only when motor 104 is operating.(In this form of the invention boiler 160 also is eliminated.) On theother hand, where the system is to be used both as a heating and acooling system, then pump 138 is provided as a separately poweredelectric pump since it must operate when boiler 160 is operating to heatthe heat exchange medium. Of course, in the heating mode of operationmotor 104 is not operating.

Of course, it is to be understood that various ignition and safetycontrols may be provided in the apparatus of the present invention, asmay be thermostatic temperature control arrangements. However, themanner of providing such ignition and thermostatic controls is a matterof choice, as they can be selected in any of a variety of manners, aswould occur to those skilled in the art. Accordingly, such controls arenot described herein in detail. In addition, it is noted that althoughunit 10 and the various components thereof are shown in detail, thefluid connections between the components are not shown in completedetail as those connections would be apparent to one skilled in the art,particularly in view of the schematic representation thereof in FIG. 2.

Accordingly, it is seen that a relatively simple system is provided forselectively operating the space conditioning system of the presentinvention as an air conditioner or as a heating system. This enables theevaporator to be placed in series with the boiler and water pump,without the loss of cooling capacity in the air conditioning mode ofoperation of the device. This is an important feature in cost savings inconstructing a system which can provide both heating and cooling, sinceit makes use of the same components in both the heating and coolingcycles. These components include the indoor heat exchanger coil, heatexchanger medium piping, water pump, ignition system, gas pressureregulator and chiller tank evaporator tank which, as

I mentioned above, provides an expansion tank within its tioner which isof a compact construction utilizing a minimum number of components.Moreover, the space conditioner of the present invention is gas poweredso that it has flexibility in providing both heating and cooling in asingle compact arrangement, utilizing relatively inexpensive naturalgas. Finally, the space conditioning system of the present invention ishighly efficient in operation.

Although an illustrative embodiment has been described herein withreference to the accompanying drawings, it is to be understood that theinvention is not limited to that precise embodiment and that variouschanges and modifications may be effectedtherein by one skilled in theart without departing from the scope or spirit of this invention.

What is claimed is:

. 1. In an air conditioning system, the combination of a central,generally cylindrical hollow core, a vertical cylindrical refrigerantvapor generator assembly adapted to receive liquid to be vaporized andbeing contained within said cylindrical core, gas fuel combustion meansdisposed within said core beneath said gen erator for heating liquidtherein, a helically wound tubularcondenser supported on'and surroundingsaid central core connected in fluid communication un'th said generatorto receive refrigerant vapor therefrom,

fan means mounted on said central core above said generator andcondenser for producing ambient air flow for cooling refrigerant vaporflowing in said condenser, a tubular refrigerant-heat exchangersupported on and surrounding said central core and connected in fluidcommunication with said condenser for receiving liquid therefrom, anevaporator, and first restriction means providing fluid communicationbetween said refrigerant heat exchanger and said evaporator, wherebycooled refrigerant liquid is supplied to said evaporator for cooling aheat exchange medium flowing therein, said refrigerant heat exchangerreceiving vapor from said evaporator countercurrently from liquidflowing therethrough from said condenser, thereby to cool said liquidfrom said condenser prior to passage thereof through said restrictionmeans; a helically wound tubular absorber supported on and surroundingsaid central core adjacent said condenser and operatively connected tosaid refrigerant heat exchanger to receive refrigerant vapor from saidevaporator, said refrigerant vapor flowing in said absorber being cooledby ambient air flow produce'dby said fan means, a helically woundtubular solution heat exchanger supported on and surrounding saidcentral core and connected in fluid communication between said generatorand said absorber for supplying weak refrigerant solution to saidabsorber for absorbing said refrigerant vapor therein, second fluid flowrestriction means located between said solution heat exchanger and said'absorber, and solution pump means for pumping refrigerant solution fromsaid absorber and supplying a first portion thereof directly to theupper portion of said generator and a second portion thereof to saidsolution heat exchanger wherein strong refrigerant solution flows inheat exchange relation to said weak solution, whereby heat is added tosaid second portion of the strong refrigerant solution prior to passageinto said generator.

2. An air conditioning system as defined in claim 1 which includes ananalyzer column contained within said generator assembly and comprisinga helically wound tubular weak solution conduit having an open lower endlocated adjacent the base of said generator for receiving weak solutiontherefrom and an upper end in fluid communication with said solutionheat exchanger for supplying weak solution thereto; and a plurality ofmass transfer plates mounted in said generator between windings of saidweak solution conduit for re moving and purifying refrigerant vapor fromsaid strong solution while weak solution flowing through said conduit iscooled by said strong solution.

3. An'air conditioning system as defined in claim 2 which includes arectifier mounted above said analyzer comprising a tubular conduit and ahollow cylindrical core, said tubular conduit being helically woundabout said core and having one end thereof connected in fluidcommunication to said pump means and an opposite end open to theinterior of said generator to supply strong solution from said pump tosaid analyzer, whereby srong solution flowing therein is heated, andrefrigerant vapor flowing upwardly in said generatoris cooled by contactwith said conduit to condense water vapor in said refrigerant vapor,thereby to purify said refrigerant vapor.

4. An air conditioning system as defined in claim 3 wherein saidsolution heat exchanger is constructed as a cylindrically wound tubewithin a tube whereby said weak solution flows countercurrently in oneof said tubes withrespect to said portion of the strong solution flowingin the other of said tubes.

5. An air conditioning system as defined in claim 1 wherein saidevaporator comprisesa generally cylindrical shell having a centralhollow cylindrical core contained within said shell to define an annularfluid flow chamber therebetween, said evaporator core having an aperturetherein providing fluid communication between the interior thereof andsaid annular fluid flow chamber, a helically wound vane secured to saidevaporator core and extending between said core and said shell, therebyto define a spiral conduit in said shell for said heat exchange mediumflowing therein; and a helically wound tubular heat exchanger concentricwith said central generator core and extending through said fluid flowchamber, said last mentioned heat exchanger being connected in fluidcommunication to said first restriction means and said refrigerant heatexchanger, thereby to cool said heat exchange medium flowing in saidfluid flow conduit.-

6. The air conditioning system as defined in claim 5 wherein saidevaporator heat exchanger comprises a fluted tube having a generallysquare cross-sectional configuration and being helically wound along itslongitudinal axis, said refrigerant and said heat exchange mediumflowing countercurrently in said fluted tube and said spiral conduitrespectively, for efficient heat exchange therebetween.

7. The air conditioning system as defined in claim 6 wherein said firstrestriction means comprises a capillary tube extending through saidevaporator central core and connected through said core to said flutedheat exchanger adjacent the base of said core, said core providing areservoir chamber for heat exchange medium flowing in said fluid flowconduit.

8. The air conditioning system as defined in claim 1 wherein said vaporgenerator assembly comprises a vessel for fluidto which heat is to betransferred and having a heat transfer wall with an outer surfacelocated in spaced relation to the interior surface of said centralcylindrical hollow core thereby to define a flue therebetween forproducts of combustion flowing upwardly from said combustion means, anda plurality of heat exchange fins located in said flue and beingoperatively connected to said vessel in intimate heat transferrelationship therewith, said heat transfer fins extending longitudinallyin the flow direction of said products of combustion to define flowpassages for said products of combustion between adjacent fins andhaving a width dimension which tapers along a predetermined patternfrom-a minimum dimension adjacent the base of said vessel to a maximumdimension adjacent the top of-said vessel, which maximum dimension isequal to the width of said flue, whereby the space between the edges ofsaid fins and the interior wallof said core decreases in the flowdirection of said products of combustion and said products of combustionencounter said edges and flow through said passageways to transfer heatto'said fins and said vessel, said predetermined width pattern for saidfins being selected in accordance with the temperature of saidproductsof combustion to allow heat to pass into the fins fromsaidproducts of combustion at the optimum rate at which heat passes throughsaid fins without damage to the fins.

9. The air conditioning system as defined in claim 8 wherein said finsare formed in pairs, with each of said pairs of fins comprising agenerally U-shaped member in section having a bight portion welded tosaid heat transfer wall of said vessel.

10. An air conditioning system comprising a generally verticallyextending refrigerant vapor generator adapted to receive strongrefrigerant solution, gas fired combustion means, below said generatorfor heating strong solution contained therein, a heat exchange condenserconnected in fluid communication with said generator for receiving andcooling refrigerant vapor from said generator, a refrigerant heatexchanger connected in fluid communication with said condenser forreceiving cooledl refrigerant liquid therefrom, a heat exchangeevaporator, and first restriction means providing fluid communicationbetween said refrigerant heat exchanger and said evaporator wherebycooled refrigerant liquid is supplied to said evaporator for cooling aheat exchange medium flowing therein, said refrigerant heat exchangerbeing adapted to receive refrigerantvapor from said evaporator and passit countercurrently with refrigerant liquid from said condenser prior topassage through said first restriction means, a heat exchange absorberconnected to said refrigerant heat exchanger in fluid communication forreceiving and cooling refrigerant vapor therefrom, a solution heatexchanger connected in fluid communication with said generator and saidabsorber for supplying weak refrigerant solution from said generator tosaid absorber for absorbing refrigerant vapor therein; second fluid flowrestriction means between said solution heat exchanger and said absorberfor maintaining a pressure differential therebetween, and a solutionpump means for pumping strong refrigerant solution from said absorberand supplying a first portion thereof directly to the upper portion ofsaid generator and a second portion thereof to said solution heatexchanger, wherein said strong refrigerant solution flows in heatexchanger relation to said weak solution whereby heat is added to saidsecond portion of the strong refrigerant solution prior to passage intosaid generator.

11. The air conditioning system as defined in claim 10 wherein saidgenerator includes an analyzer column contained therein comprising ahelically wound tubular weak solution conduit having an open lower endlocated adjacent the base of said generator for receiving weak solutiontherefrom'and an upper end-in fluid communication with said solutionheat exchanger for supplying weak solution thereto; anda plurality ofmass transfer plates mounted in said generator between windings of saidweak solution conduit to remove and purify refrigerant vapor from saidstrong solution while weak solution flowing through said conduit iscooled by said strong solution.

12. The air conditioning system as defined in claim 11 wherein saidgenerator further includes a rectifier mounted therein above saidanalyzer, said rectifier comprising a tubular conduit and a hollowcylindrical core, said tubular conduit being helically wound about saidcore and having one end thereof connected in fluid communication to saidpump means and an opposite end to open to the interior of said generatorto supply strong solution from said pump to said analyzer, wherebystrong solution flowing therein is heated, and refrigerant vapor flowingupwardly in said generator is cooled by contact with said conduittocondense water vapor in said refrigerant vapor, thereby to purify saidrefrigerant vapor.

13. The air conditioning system as defined in claim 12 wherein saidfirst restrictor means comprises a capil lary tube extending throughsaid evaporator central core and connected through said core to saidfluted heat exchanger adjacent the base of said core, said coreproviding a reservoir chamber for heat exchange medium flowing in saidfluid flow conduit.

14. The air conditioning system as defined in claim 10 wherein saidevaporator comprises a generally cylindrical shell having a centralhollow cylindrical core containedvwithin said shell to define an annularfluid flow chamber therebetween, said evaporator core having an aperturetherein providing fluid communication between the interior thereof andsaid annular fluid flow chamber, a helically wound vane secured to saidevaporator core and extending between said core and said shell, therebyto define a helical conduit in said shell for said heat exchangemediumflowing therein; and a helically wound tubular heat exchangerconcentric with said central evaporator core and extending through saidfluid flow chamber, said last mentioned heat exchanger being connectedin fluid communication to said first restriction means and saidrefrigerant heat exchanger, thereby to cool said heat exchange mediumflowing in said fluid flow conduit.

15. The air conditioning system as defined in claim 14 wherein saidevaporator heat exchanger comprises a fluted tube having a generallysquare cross-sectional configuration and being helically wound along itslongitudinal axis, said refrigerant vapor and said heat exchange mediumflowing countercurrently in said fluted tube and said spiral conduitrespectively for efficient heat exchange therebetween.

16. The air conditioning system as defined in claim 10 wherein saidvapor generator comprises a pressure vessel for refrigerant solution towhich heat is to be transferred and having a heat transfer wall with anouter surface, confining wall means surrounding said vessel and having awall portion spaced from said outer surface, thereby to define a fluetherebetween for products of combustion flowing upwardly from said gasfired combustion means, and a plurality of heat exchange fins located insaid flue and being operatively connected to said vessel in intimateheat transfer relationship therewith, said heat transfer fins extendinglongitudinally in the flow direction of said products of combustion todefine flow passages for said products of combustion between adjacenttins and having a width dimension extending between said pressure vesselsaid confining wall which tapers along a predetermined pattern from aminimum dimension adjacent the base of said vessel to a maximumdimension adjacent the top of said vessel, which maximum dimension isequal to the width of said flue, whereby the space between the edges ofsaid fins and said confining means wall portion decreases in the flowdirection of said products of combustion, whereby said products ofcombustion encounsaid pairs of fins comprising a generally U-shapedmember in section having a bight portion welded to said heat transferwall of said vessel.

UNITE STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent 3,828,575Dated August 13, 1974 Non nan D. Malcosky; Ronald H. McLean; ln fl N.Sinh Chun M; Auh

It is certified thatietror appears in the above-identified patent andthat said Lettets' Patent arehereby corrected as shown below:

' In the heading below United States Patent "Mallosk y et a1. is changegl to --Ma1cos ky et a1.

Signed and 'sealed this 19th day of November 1974.

(SEAL) Attest:

MccoY M. (mason JR. Attesting Office; I, v Q

' ,c.. MARSHALL DANN Comissioaer of Patents USCOMM-DC 60376-P59 FoRMpo-wsouo-ss) 1 i v i ".5. GOVFINIIINT PRINTING OFFICE I", O-JFO-SM,

1. In an air conditioning system, the combination of a central,generally cylindrical hollow core, a vertical cylindrical refrigerantvapor generator assembly adapted to receive liquid to be vaporized andbeing contained within said cylindrical core, gas fuel combustion meansdisposed within said core beneath said generator for heating liquidtherein, a helically wound tubular condenser supported on andsurrounding said central core connected in fluid communication with saidgenerator to receive refrigerant vapor therefrom, fan means mounted onsaid central core above said generator and condenser for producingambient air flow for cooling refrigerant vapor flowing in saidcondenser, a tubular refrigerant heat exchanger supported on andsurrounding said central core and connected in fluid communication withsaid condenser for receiving liquid therefrom, an evaporator, and firstrestriction means providing fluid communication between said refrigerantheat exchanger and said evaporator, whereby cooled refrigerant liquid issupplied to said evaporator for cooling a heat exchange medium flowingtherein, said refrigerant heat exchanger receiving vapor from saidevaporator countercurrently from liquid flowing therethrough from saidcondenser, thereby to cool said liquid from said condenser prior topassage thereof through said restriction means; a helically woundtubular absorber supported on and surrounding said central core adjacentsaid condenser and operatively connected to said refrigerant heatexchanger to receive refrigerant vapor from said evaporator, saidrefrigerant vapor flowing in said absorber being cooled by ambient airflow produced by said fan means, a helically wound tubular solution heatexchanger supported on and surrounding said central core and connectedin fluid communication between said generator and said absorber forsupplying weak refrigerant solution to said absorber for absorbing saidrefrigerant vapor therein, second fluid flow restriction means locatedbetween said solution heat exchanger and said absorber, and solutionpump means for pumping refrigerant solution from said absorber andsupplying a first portion thereof directly to the upper portion of saidgenerator and a second portion thereof to said solution heat exchangerwherein strong refrigerant solution flows in heat exchange relation tosaid weak solution, whereby heat is added to said second portion of thestrong refrigerant solution prior to passage into said generator.
 2. Anair conditioning system as defined in claim 1 which includes an analyzercolumn contained within said generator assembly and comprising ahelically wound tubular weak solution conduit having an open lower endlocated adjacent the base of said generator for receiving weak solutiontherefrom and an upper end in fluid communication with said solutionheat exchanger for supplying weak solution thereto; and a plurality ofmass transfer plates mounted in said generator between windings of saidweak solution conduit for removing and purifying refrigerant vapor fromsaid strong solution while weak solution flowing through said conduit iscooled by said strong solution.
 3. An air conditioning system as definedin claim 2 which includes a rectifier mounted above said analyzercomprising a tubular conduit and a hollow cylindrical core, said tubularconduit being helically wound about said core and having one end thereofconnected in fluid communication to said pump means and an opposite endopen to the interior of said generator to supply strong solution fromsaid pump to said analyzer, whereby srong solution flowing therein isheated, and refrigerant vapor flowing upwardly in said generator iscooled by contact with said conduit to condense water vapor in saidrefrigerant vapor, thereby to purify said refrigerant vapor.
 4. An airconditioning system as defined in claim 3 wherein said solution heatexchanger is constructEd as a cylindrically wound tube within a tubewhereby said weak solution flows countercurrently in one of said tubeswith respect to said portion of the strong solution flowing in the otherof said tubes.
 5. An air conditioning system as defined in claim 1wherein said evaporator comprises a generally cylindrical shell having acentral hollow cylindrical core contained within said shell to define anannular fluid flow chamber therebetween, said evaporator core having anaperture therein providing fluid communication between the interiorthereof and said annular fluid flow chamber, a helically wound vanesecured to said evaporator core and extending between said core and saidshell, thereby to define a spiral conduit in said shell for said heatexchange medium flowing therein; and a helically wound tubular heatexchanger concentric with said central generator core and extendingthrough said fluid flow chamber, said last mentioned heat exchangerbeing connected in fluid communication to said first restriction meansand said refrigerant heat exchanger, thereby to cool said heat exchangemedium flowing in said fluid flow conduit.
 6. The air conditioningsystem as defined in claim 5 wherein said evaporator heat exchangercomprises a fluted tube having a generally square cross-sectionalconfiguration and being helically wound along its longitudinal axis,said refrigerant and said heat exchange medium flowing countercurrentlyin said fluted tube and said spiral conduit respectively, for efficientheat exchange therebetween.
 7. The air conditioning system as defined inclaim 6 wherein said first restriction means comprises a capillary tubeextending through said evaporator central core and connected throughsaid core to said fluted heat exchanger adjacent the base of said core,said core providing a reservoir chamber for heat exchange medium flowingin said fluid flow conduit.
 8. The air conditioning system as defined inclaim 1 wherein said vapor generator assembly comprises a vessel forfluid to which heat is to be transferred and having a heat transfer wallwith an outer surface located in spaced relation to the interior surfaceof said central cylindrical hollow core thereby to define a fluetherebetween for products of combustion flowing upwardly from saidcombustion means, and a plurality of heat exchange fins located in saidflue and being operatively connected to said vessel in intimate heattransfer relationship therewith, said heat transfer fins extendinglongitudinally in the flow direction of said products of combustion todefine flow passages for said products of combustion between adjacentfins and having a width dimension which tapers along a predeterminedpattern from a minimum dimension adjacent the base of said vessel to amaximum dimension adjacent the top of said vessel, which maximumdimension is equal to the width of said flue, whereby the space betweenthe edges of said fins and the interior wall of said core decreases inthe flow direction of said products of combustion and said products ofcombustion encounter said edges and flow through said passageways totransfer heat to said fins and said vessel, said predetermined widthpattern for said fins being selected in accordance with the temperatureof said products of combustion to allow heat to pass into the fins fromsaid products of combustion at the optimum rate at which heat passesthrough said fins without damage to the fins.
 9. The air conditioningsystem as defined in claim 8 wherein said fins are formed in pairs, witheach of said pairs of fins comprising a generally U-shaped member insection having a bight portion welded to said heat transfer wall of saidvessel.
 10. An air conditioning system comprising a generally verticallyextending refrigerant vapor generator adapted to receive strongrefrigerant solution, gas fired combustion means below said generatorfor heating strong solution contained therein, a heat exchange condenserconnected in fluid communication with said generatOr for receiving andcooling refrigerant vapor from said generator, a refrigerant heatexchanger connected in fluid communication with said condenser forreceiving cooled refrigerant liquid therefrom, a heat exchangeevaporator, and first restriction means providing fluid communicationbetween said refrigerant heat exchanger and said evaporator wherebycooled refrigerant liquid is supplied to said evaporator for cooling aheat exchange medium flowing therein, said refrigerant heat exchangerbeing adapted to receive refrigerant vapor from said evaporator and passit countercurrently with refrigerant liquid from said condenser prior topassage through said first restriction means, a heat exchange absorberconnected to said refrigerant heat exchanger in fluid communication forreceiving and cooling refrigerant vapor therefrom, a solution heatexchanger connected in fluid communication with said generator and saidabsorber for supplying weak refrigerant solution from said generator tosaid absorber for absorbing refrigerant vapor therein; second fluid flowrestriction means between said solution heat exchanger and said absorberfor maintaining a pressure differential therebetween, and a solutionpump means for pumping strong refrigerant solution from said absorberand supplying a first portion thereof directly to the upper portion ofsaid generator and a second portion thereof to said solution heatexchanger, wherein said strong refrigerant solution flows in heatexchanger relation to said weak solution whereby heat is added to saidsecond portion of the strong refrigerant solution prior to passage intosaid generator.
 11. The air conditioning system as defined in claim 10wherein said generator includes an analyzer column contained thereincomprising a helically wound tubular weak solution conduit having anopen lower end located adjacent the base of said generator for receivingweak solution therefrom and an upper end in fluid communication withsaid solution heat exchanger for supplying weak solution thereto; and aplurality of mass transfer plates mounted in said generator betweenwindings of said weak solution conduit to remove and purify refrigerantvapor from said strong solution while weak solution flowing through saidconduit is cooled by said strong solution.
 12. The air conditioningsystem as defined in claim 11 wherein said generator further includes arectifier mounted therein above said analyzer, said rectifier comprisinga tubular conduit and a hollow cylindrical core, said tubular conduitbeing helically wound about said core and having one end thereofconnected in fluid communication to said pump means and an opposite endto open to the interior of said generator to supply strong solution fromsaid pump to said analyzer, whereby strong solution flowing therein isheated, and refrigerant vapor flowing upwardly in said generator iscooled by contact with said conduit to condense water vapor in saidrefrigerant vapor, thereby to purify said refrigerant vapor.
 13. The airconditioning system as defined in claim 12 wherein said first restrictormeans comprises a capillary tube extending through said evaporatorcentral core and connected through said core to said fluted heatexchanger adjacent the base of said core, said core providing areservoir chamber for heat exchange medium flowing in said fluid flowconduit.
 14. The air conditioning system as defined in claim 10 whereinsaid evaporator comprises a generally cylindrical shell having a centralhollow cylindrical core contained within said shell to define an annularfluid flow chamber therebetween, said evaporator core having an aperturetherein providing fluid communication between the interior thereof andsaid annular fluid flow chamber, a helically wound vane secured to saidevaporator core and extending between said core and said shell, therebyto define a helical conduit in said shell for said heat exchange mediumflowing therein; and a helically wound tubular heat exchanger concentricwith said central Evaporator core and extending through said fluid flowchamber, said last mentioned heat exchanger being connected in fluidcommunication to said first restriction means and said refrigerant heatexchanger, thereby to cool said heat exchange medium flowing in saidfluid flow conduit.
 15. The air conditioning system as defined in claim14 wherein said evaporator heat exchanger comprises a fluted tube havinga generally square cross-sectional configuration and being helicallywound along its longitudinal axis, said refrigerant vapor and said heatexchange medium flowing countercurrently in said fluted tube and saidspiral conduit respectively for efficient heat exchange therebetween.16. The air conditioning system as defined in claim 10 wherein saidvapor generator comprises a pressure vessel for refrigerant solution towhich heat is to be transferred and having a heat transfer wall with anouter surface, confining wall means surrounding said vessel and having awall portion spaced from said outer surface, thereby to define a fluetherebetween for products of combustion flowing upwardly from said gasfired combustion means, and a plurality of heat exchange fins located insaid flue and being operatively connected to said vessel in intimateheat transfer relationship therewith, said heat transfer fins extendinglongitudinally in the flow direction of said products of combustion todefine flow passages for said products of combustion between adjacentfins and having a width dimension extending between said pressure vesselsaid confining wall which tapers along a predetermined pattern from aminimum dimension adjacent the base of said vessel to a maximumdimension adjacent the top of said vessel, which maximum dimension isequal to the width of said flue, whereby the space between the edges ofsaid fins and said confining means wall portion decreases in the flowdirection of said products of combustion, whereby said products ofcombustion encounter said edges and flow through said passageways totransfer heat to said fins and said vessel, said predetermined widthpattern for said fins being selected in accordance with the temperatureof said products of combustion to allow heat to pass into the fins fromsaid products of combustion at the optimum rate at which heat passesthrough said fins without damage to the fins.
 17. The air conditioningsystem as defined in claim 10 wherein said fins are formed in pairs,with each of said pairs of fins comprising a generally U-shaped memberin section having a bight portion welded to said heat transfer wall ofsaid vessel.